tipyoudaoicibaDictYouDict[tip 词源字典]
tip: English has three distinct words tip, two of them possibly related. Tip ‘extremity’ [15] was probably borrowed from Old Norse typpi. This was descended from prehistoric Germanic *tupp- ‘upper extremity’ (source also of English top and toupee). Tip ‘touch lightly’ [13] (as in ‘tip-and-run cricket’) may have been borrowed from Low German tippen, although it could be the same word as tip ‘extremity’ (from the notion of ‘just touching something with the tip of something else’).

It was used in 17th-century underworld argot for ‘give’ (as in ‘tip someone the wink’), and this evolved in the 18th century to ‘give a gratuity’. The antecedents of tip ‘overturn’ [14] (originally tipe) are not known, although the fact that it first appeared in northern dialects suggests that it may have been borrowed from a Scandinavian language. The derived tipsy [16] denotes etymologically ‘liable to fall over’.

=> top, toupee; tipsy[tip etymology, tip origin, 英语词源]
tip (v.1)youdaoicibaDictYouDict
c. 1300, "to knock down, overturn, topple, knock askew" (transitive), of uncertain origin, possibly from Scandinavian (compare Swedish tippa "to tip, dump"), or from a special use of tip (n.). Intransitive sense of "to fall over, be overturned" is from mid-15c. Related: Tipped; tipping. To tip the scales at "weigh (so much" is from 1879. Tipping point attested by 1972. To tip (one's) hand "reveal one's intentions" is from 1907, an image from poker-playing.
tip (n.1)youdaoicibaDictYouDict
c. 1400, "extreme end of something, top of something round or pointed, metal attachment to the end of something," from Middle Low German or Middle Dutch tip "utmost point, extremity, tip" (compare German zipfel, a diminutive formation); or from a Scandinavian source (compare Old Norse typpi).
tip (v.2)youdaoicibaDictYouDict
"give a small present of money to," c. 1600, originally "to give, hand, pass," thieves' cant, perhaps from tip (v.3) "to tap." The meaning "give a gratuity to" is first attested 1706. The noun in this sense is from 1755; the noun meaning "piece of confidential information" is from 1845; and the verb in the sense "give private information to" is from 1883.

The popularity of the tale of the word's supposed origin as an acronym in mid-18th century English taverns seems to be no older than Frederick W. Hackwood's 1909 book "Inns, Ales and Drinking Customs of Old England," where it was said to stand for To insure promptitude (in the form to insure promptness the anecdote is told from 1946). A reviewer of the book in the "Athenaeum" of Oct. 2, 1909, wrote, "We deprecate the careless repetition of popular etymologies such as the notion that "tip" originated from an abbreviated inscription on a box placed on the sideboard in old coaching-inns, the full meaning of which was "To Insure Promptitude." Also see here.
tip (v.3)youdaoicibaDictYouDict
c. 1200, "to strike, occur suddenly," of uncertain origin, possibly from Low German tippen "to poke, touch lightly," related to Middle Low German tip "end, point," and thus connected to tip (n.); or else related to tap (v.1). Meaning "strike sharply but lightly" is from 1560s. Sports sense is from 1816, originally in cricket. Related: Tipped; tipping.
tip (n.2)youdaoicibaDictYouDict
"a light, sharp blow or tap," mid-15c., from tip (v.3).
tip (v.4)youdaoicibaDictYouDict
"put a tip on, adorn with a tip," late 14c., from tip (n.) or Old Norse typpa. Related: Tipped; tipping.